I published an article on a MIDI-controlled xylophone, called the
Xylotron, in the October 2000 issue of Nuts & Volts magazine,
http://www.nutsvolts.com/

Since then, the Xylotron circuitry has been used to MIDI enable and
automate a number of musical instruments, including a harpsichord, a
calliope and a pipe organ.  Several people have asked me whether the
Xylotron circuitry can play music if not connected to a computer.

The original design did not have the ability to play music unless it
was connected to a computer and MIDI data was being downloaded in real
time.  After lugging a computer around to several demonstrations,
I came to the conclusion that the Xylotron should have a computer
independent mode of operation.

A new article will be published in Nuts & Volts which will discuss the
circuit and software modifications necessary to give the Xylotron II
the ability to hear 683 seconds or 4096 notes of MIDI music, remember
it on a 32k memory chip, and replay it on command _without_ being
connected to a computer.  This article will also provide some useful
information on interfacing a large external serial EEPROM memory chip
to a Microchip PIC.

Until the article is published, the source code and some pictures are
available at the Xylotron home page:  http://www2.netdoor.com/~rlang

Bob Lang